Start your game with the -debug command line parameter. To do this, edit your properties to read avp.exe -debug.
Enter the cheat console by pressing ~ + [F12] then enter these codes when using the character listed:
effect / character use / code
Create CPU controlled Alien / Any / alienbot
All weapons and ammo / Any / giveallweapons
God mode / Any / god
Create light aura; repeat for brighter aura / Any / light
Create a CPU controlled Marine / Any / marinebot
Player invisible to all opponents / Any / observer
Create CPU controlled Predator1 / Any / predobot
Create CPU controlled Predator-Alien1 / Any / predalienbot
Create CPU controlled Praetorian Alien1 / Any / praetorianbot
Create CPU controlled Xenoborg1 / Any / xenoborg
Display level coordinates / Any / showcoords
Display frame rate / Any / showfps
Display number of rendered polygons / Any / showpolycount
Replenish energy supply / Predator / gimme_charge
God mode / Marine / freakoftheunivers
God mode / Predator / skullcollector
God mode / Alien / theonedeadlycreautureevercreated
Become Final Xenomorph / Alien / winneroftheonegreatbattleoftheuniverse
List in-game help / Any / listvar
List cheat commands / Any / listcmd
Change motion tracker volume / Marine / motiontrackervolume <0.00-1.00>
Change motion tracker speed / Marine / motiontrackerspeed <0-16>
Toggle crouch and crawl / Alien / crouchmode <0 or 1>
Change game speed / Any / timescale <0.0-1.0>
Toggle wire frame mode / Any / wireframemode <0 or 1>
Toggle doppler shift on Alien sounds / Any / dopplershift <0 or 1>
Adjust amount of red in sky / Any / sky_red
Adjust amount of green in sky / Any / sky_green
Adjust amount of blue in sky / Any / sky_blue